题解 | #对称的二叉树#

递归

class Solution {
public:
    bool isSymmetrical2(TreeNode* l, TreeNode* r) {
        if ((l != nullptr) ^ (r != nullptr)) return false;
        if (!l && !r) return true;
        return l->val == r->val && isSymmetrical2(l->left, r->right) && isSymmetrical2(l->right, r->left);
    }

    bool isSymmetrical(TreeNode* pRoot) {
        if (!pRoot) return true;
        return isSymmetrical2(pRoot->left, pRoot->right);
    }

};